The paper explores the sources of law used by international law-enforcing bodies, thus informing our prophecies about their output. It discusses the practice of international and domestic bodies, who claim to enforce international law, or can be plausibly described as doing just so, and juxtaposes the sources of international law norms on which such bodies rely with the list of international law sources found in article 38(1) of the ICJ Statute. It offers in this connection two inter-related surveys: A categorization of the main bodies that engage in international law-enforcement, and an overview of the process of law-enforcement pertaining to two sets of norms that appear to enjoy exceptional prominence in the world of law-enforcement – international judgments and resolutions of international organizations (IGOs). These surveys underlie the contention that article 38 – the standard reference point for studying the sources of international law – does not necessarily predict well which international law norms are likely to be invoked in practice by law-enforcement-bodies. The paper concludes with a discussion of some of the explanations for the differences between the general list of sources of international law and the sources actually relied upon by international law-enforcement bodies.